Barista versions of plant milks often have added vegetable oils to help mimic the fat–protein interaction in dairy. It's what makes the milk foam stable and the liquid feel creamy.

"Every time we hire a barista, we have a big pool of applicants to choose from," says Jessica Novak, a store manager at Starbucks in North York, Ont. Challenges: The early morning hours can be tough.

If I ever questioned what I was doing working as a barista, I would recall the words of an old friend and restaurateur who understands true hospitality. She applauded me for making a difference in ...